Mobile communications

ABSTRACT

National mobile networks are provided with a proxy location register for storing user identities in association with respective network identities. Users have an associated “mobile home” for storing call handling instructions and messages recorded by a Voicemail system. When a user roams from a current host network to a visited network, he may request that his mobile home be moved from its current location, most likely that current host network, to the visited network, and retrieval of any messages that have been left for that user can now be done without involving real-time use of international links between networks. Furthermore, when the mobile home has moved, its new location, with or without call handling instructions, can be manually or automatically notified to all other networks, or a subset, for location register updating. The use of this location information can avoid tromboning over expensive international links, and the call handling instructions enables remote networks to decide if a connection is to be attempted to a destination network.

This application is the U.S. national phase of international applicationPCT/GB01/01233 filed Mar. 21, 2001 which designated the U.S.

The present invention relates to communications networks, particularlybut not exclusively communications networks for providing mobiletelephone communication, and to methods of operating such networks.

Mobile communications as a concept embraces not only mobility of a userwithin his home network, but also the ability for callers to he able tocommunicate with that user when he has moved to, i.e. registered with, aremote network, referred to as a visited network. This is known asroaming. On a global scale, one can talk about a global mobile networkcomprising a multiplicity of national mobile networks interconnected byinternational links.

Callers dial the user's globally unique telephone number, and theircalls are, routed to the user's home network, where a register is keptof the current locations of all the users having telephone numbersassociated with that home network, and that call is then extended to theuser's visited network. This is referred to as tromboning, i.e. the callgoes into the home network and out to the visited network, withattendant international call charges and extended call set up units, andit happens even when the caller is in that visited network.

Also, if a roaming user accesses a messaging service in his home networkand retrieves his messages, which might be voice or multimedia format,each of these has to be transmitted in real time over internationallinks, and could be subject to congestion.

U.S. Pat. No. 6,038,456 (Colby et al.) discloses a solution to theproblem of issuing a user with another mobile telephone number (MSISDN)for use for, e.g. data calls, when the Home Location Register (HLR) unitwhich records that user's original MSISDN has no spare. Instead of theknown practice of a network operator (carrier) ordering a large quantityof phones from a supplier, say 1000, and associating a correspondingblock of MSISDNs with a particular HLR unit, Colby et al. proposeallocating MSISDNs to HLR units on an individual basis and having alookup table (called a Register Unit) which signalling transfer pointsinterrogate by the dialed MSISDN in order to find which HLR unit toaccess for the called user's details.

U.S. Pat. No. 5,915,220 (Chelliah) discloses a mobile network in whichthe Home Location Register (HLR) has a last visited list of MobileSwitching Centres (MSC) and the deregistration procedure involving aRegistration cancel Message is modified such that an MSC at which a userwas previously registered does not delete the user's service profileupon receipt from the HLR of a Registration Cancel Message. Thus, if theuser revisits an MSC, the HLR knows from its last visited list that thatMSC already stores a copy of the user's service profile, and does notsend another copy.

According to a first aspect of the present invention there is provided amethod of operating a communications network interconnected with aplurality of other communications networks, the method comprising thesteps of:

establishing data storage and a location register having entriescomprising a user identifier and an associated location identifier; and

responding to an originating call to a called user by

accessing the location register in accordance with a user identifier forthat called user to ascertain the corresponding associated locationidentifier, and it there is a corresponding entry, and

performing connection set up on the basis that the destination networkfor the called user is that communications network which corresponds tothat ascertained location identifier;

the method being characterised in that:

user-associated relocatable data packages currently located at saidcommunications network are stored in said data storage, and

each said location identifier represents the most recent location knownto said communications network of the corresponding user-associaterelocatable data package;

and the method being characterised by the steps of:

receiving from a said other communications network a move request inrespect of a specified user, and in response,

removing that specified user's associated relocatable data package fromthe data storage, and

relocating that data package to said other communications network.

The use of the location register and the relocatable data packagealleviates the above described situations. The user's relocatable datapackage can be relocated at a time convenient to the network operators,e.g. when there is little traffic between the home network and thevisited network, and after it has been moved the user will then be ableto retrieve his messages from a local storage of his data package,without involving any international links in his real time retrieval ofthe messages.

Preferably, there is included the step of responding to receipt fromsaid other communications network of a location register update messagein respect that specified user by changing the location identifier ofthat specified user's entry to that for said other communicationsnetwork.

There may be included the steps of:

receiving a request from a user, currently registered with saidcommunications network as a visitor, for that visiting user's associatedrelocatable data package to be relocated to said communications network;

in response to that receipt, accessing the location register inaccordance with an identifier for that visiting user; and, if there is acorresponding entry,

ascertaining the location identifier of that corresponding entry, and

sending a move request in respect of that visiting user to the othercommunications network corresponding to the ascertained locationidentifier,

else, requesting of at least one of the other communications networks alocation identifier for the other communications network currentlystoring that visiting user's associated relocatable data package,

upon receipt of the requested location identifier, sending a moverequest in respect of that visiting user to the other communicationsnetwork corresponding to the received location identifier; and

upon receipt of that user's associated relocatable data package, storingit in the data storage.

According to a second aspect of the present invention there is provideda method of operating a communications network interconnected with aplurality of other communications networks, at least one of said othercommunications networks operating in accordance with the first aspect ofthe present invention, the method comprising the steps of:

receiving a request from a user, currently registered with saidcommunications network as a visitor, for that visiting user's associatedrelocatable data package to be relocated to said communications network;

in response to that receipt, requesting of at least one of the othercommunications networks a location identifier for the othercommunications network currently storing that visiting user's associatedrelocatable data package;

upon receipt of the requested location identifier, sending to the othercommunications network corresponding to the received location identifiera move request for that user's associated relocatable data package to berelocated to said communications network, and

upon receipt of that user's associated relocatable data package storingit in association with a user identifier for that user.

There may be included the steps of retrieving instructions from areceived user-associated relocatable data package, and in accordancewith those instructions, effecting modification of each of apredetermined set of the communications networks.

Preferably, the step of effecting modification comprises generating amessage and sending that message to each of said predetermined set ofthe communications networks other than that communications network whichperforms the step of retrieving instructions.

The retrieved instructions may comprise instructions for modifying therespective location registers by changing the respective stored locationidentifier to that of the network which performs the step of retrievinginstructions.

The retrieved instructions may comprise instructions compriseinstructions for storing call handling information and modifying therespective location registers to associate that stored call handlinginformation with the entry corresponding to the received user-associatedrelocatable data package.

The requesting step may comprise sending a query message in respect ofthat visiting user to that one of said other communications networkswhich corresponds to the global address of that visiting user.

Alternatively, the requesting step may comprise sending a query messagein respect of that visiting user to each of said other communicationsnetworks.

There may be included the steps of connecting calls for a particularuser, whose user-associated relocatable data package is currentlylocated at said communications network, to a message recording serviceand recording messages, and incorporating those recorded messages withinthat particular user's relocatable data package.

According to a third aspect of the present invention there is provided acommunications network arranged for interworking with a plurality ofother communications networks and employing a global addressing scheme,the network comprising:

a location register arranged to store entries each comprising a useridentifier and an associated location identifier; and

means arranged to respond to an originating call to a called user by

accessing the location register in accordance with an identifier forthat called user and ascertaining the associated location identifier,and

performing connection set up on the basis that the destination networkfor the called user is that communications network which corresponds tothat ascertained location identifier;

wherein the network is characterised by:

data storing means arranged to store user-associated relocatable datapackages;

means arranged to respond to receipt from a said other communicationsnetwork of a move request in respect of a specified user'associatedrelocatable data package stored in the data storing means by

removing that specified user's associated relocatable data package fromthe data storing means, and

relocating that data package to said other communications network.

There may be included means arranged to respond to receipt from saidother communications network of a message in respect of that specifieduser and containing location register update information by changing thelocation identifier of that specified user's entry to that for saidother communications network.

There may be included means arranged to respond to a request from avisiting user for that visiting user's associated relocatable datapackage to be moved to said communications network, by

accessing the location register in accordance with an identifier forthat visiting user,

and, if there is a corresponding entry,

ascertaining the associated location identifier, and

sending a move request in respect of that visiting user to a said othercommunications network corresponding to the ascertained locationidentifier, else

requesting of at least one of the other communications networks alocation identifier for the other communications network currentlystoring that visiting user's associated relocatable data package, and,upon receipt of the requested location identifier,

sending a move request in respect of that visiting user to that othercommunications network corresponding to that received locationidentifier.

According to a fourth aspect of the present invention there is provideda communications network arranged for interworking with a plurality ofother communications networks, at least one of said other communicationsnetworks being in accordance with the third aspect of the presentinvention, said communications network comprising:

a location register arranged to store entries each comprising a useridentifier and an associated location identifier; and

means arranged to respond to an originating call to a called user by

accessing the location register in accordance with an identifier forthat called user and ascertaining the associated location identifier,and

performing Connection Set up on the basis that the destination networkfor the called user is that communications network which corresponds tothat ascertained location identifier;

wherein the network is characterised by:

data storing means, and

means arranged to respond to a request from a user, currently registeredwith said communications network as a visitor, for that user'sassociated relocatable data package to be moved to said communicationsnetwork by

requesting of at least one of the other communications networks alocation identifier for the other communications network currentlystoring that visiting user's associated data package,

upon receipt of the requested network identifier, sending to the othercommunications network corresponding to the received location identifiera move request for that user's associated data package to be relocatedto said communications network, and

upon receipt of that user's associated relocatable data package, storingit in said data storing means in association with a user identifier forthat user.

There may be included means arranged to retrieve instructions from areceived user's relocatable data package, and in accordance with thoseinstructions, to effect modification of each of a predetermined set ofthe communications networks.

Preferably, the retrieving and modifying means is arranged to effectsaid modification by generating a message and sending that message toeach of said predetermined set of the communications networks other thanitself.

Preferably, the retrieving and modifying means is arranged in accordancewith those instructions, to modify the respective location register bychanging the respective stored location identifier to its own locationidentifier.

Preferably, when a network of the present invention is for use whenthose instructions comprise instructions for storing call handlinginformation, the retrieving and modifying means is arranged to modifythe respective location register to associate such stored call handlinginformation with the entry corresponding to the received user-associatedrelocatable data package.

A network of the present invention may be arranged to make said requestof at least one of the other communications networks for said networkidentifier by sending a query message in respect of that visiting userto that one of said other communications networks which corresponds tothe global address of that visiting user.

A network of the present invention may be arranged to make said requestof at least one of the other communications networks for said networkidentifier by sending a query message in respect of that visiting userto each of said other communications networks.

A network of the present invention may have a message recording system,and included means arranged to respond to messages recorded by themessage recording system in respect of a particular user whoserelocatable data package is currently stored in said data storing meansby incorporating those recorded messages within that particular user'srelocatable data package.

A specific embodiment of the present invention will now be described byway of example with reference to the drawings in which:

FIG. 1 is a block diagram of some of the components of a GSM network;

FIG. 2 is a block diagram of some of the components of a networkaccording to the present invention;

FIG. 3 is a block diagram of part of the network of FIG. 2.

In FIG. 1, there is shown a GSM network 10 constituted by foursubsystems, namely, Mobile Station Subsystem (MSS) 12, Base StationSubsystem (BSS) 14, Network and Switching Subsystem (NSS) 16 andOperation Subsystem (OSS) 18. The GSM system is well known to theskilled person in the art and will not be described in detail. However,should any reader require more information, he will find a number ofpublications on GSM, particularly, “The GSM System for MobileCommunications” by M. Mouly and M.-B. Pautet, published 1992 by theauthors.

The MSS 12 comprises a plurality of conventional mobile stations 20,also referred to as mobile telephones, or just mobiles.

The BSS 14 comprises a plurality of base transceiver stations 22 and aplurality of base station controllers 24, only one which is shown. Eachof the base station controllers 24 is connected to the NSS 16 and to aplurality of the, base transceiver stations 22.

The NSS 16 comprises an exchange system 26 and user and terminalequipment databases 28. The exchange system 26 comprises a plurality ofinterconnected mobile services switching centres 30, only one which isshown, which are connected to the user and terminal equipment databases28.

The OSS 18 comprises an operation and maintenance centre 32 which isconnected, via a data network 34, to the BSS 14 and the NSS 16.

The user and terminal equipment databases 28 comprise a home locationregister 36, a visitor location register 38 and an equipment identityregister 40.

The home location register 36 is a database which contains user-specificinformation relevant to the provision of telecommunications services andthe current location, the former identifying whether a given teleserviceor bearer service can be provided for a user.

The visitor location register 38 temporarily stores subscription datafor users who are normally registered with a different home GSM networkand who are currently registered with the GSM network 10, i.e. under aroaming arrangement.

When a visiting user within the operational area of the GSM network 10and wants to use one or more of its GSM services, he swithes on hismobile telephone 20. The mobile telephone 20 performs in known manner aregistration procedure in which the user's Mobile Station InternationalISDN mumber and the International Mobile Station Identity are retrievedfrom the Subscriber Identity Module (SIM) card in the mobile telephone20. From this information, the user's home GSM network is ascertained,and the visited network sends a message to the home network. The homenetwork responds by accessing its home location register, retrieving asubset of the user's subscription data, and sending the retrieved subsetof subscription data to the visitor location register 38 of the visitednetwork for temporary storage. Typically, this subset contains securitydata for the authentication of the user.

In the existing GSM system the user can subscribe to an answeringservice for recording messages, e.g. Voicemail, when calls cannot bedelivered to his mobile telephone, and in this case he can retrieverecorded messages by calling an access number for that service, withappropriated authentication, as is known. The messages are recorded in aVoicemail system 42 in the user's home GSM network, and should the userroam to a foreign GSM network and retrieve his messages, they have to begenerated individually upon request by the user and relayed acrossinternational links to that foreign GSM network in real time during theretieval call to the Voicemail system 42.

FIG. 2 is a block schematic of a GSM network 100, which is similar tothe GSM network 10. It comprises corresponding subsystems MSS 112, BSS114, NSS 116 and OSS 118, with its components 120 to 134 and 142,corresponding to components 20 to 34, 40 and 42 of the network of FIG.1, and it has been modified in accordance with the present invention, asdescribed below.

In FIG. 3, there is shown user and terminal equipment databases 128which is part of the NSS 116. Instead of a visitor location registerthere is a proxy location register (PRL) 148, and a data store 150 withan associate data store manager 152 arranged to allocated dynamically arespective memory area 154 of the data store 150 for each user currentlyregistered with the GSM network 100, i.e. both home users and visitingusers. Instead of a home location register there is an allocationregister 146 of users who have been allocated mobile telephone numbersassociated with that network. Thus, any GSM network 100 can ascertainfrom a mobile telephone number which network had allocated that number,such an allocating network is referred to as that mobile's home network,and the numbering scheme is referred to as a global addressing scheme.The PLR 148 and the data store 150 together constitute a storing meansof the present invention.

In this embodiment, the GSM network 100 comprises a Voicemail system 142linked to the NSS 116 and the data store manager 152. For each currentlyregistered user who subscribes to the Voicemail service, relevantsubscription information is recorded in a respective user-associatedprofile stored in the allocation register 146.

Suppose that a call attempt is made to such a currently registered user.The NSS 116 accesses the respective user-associated profile to ascertainhow that user requires the call to be handled, discovers that is it isto be delivered to the Voicemail serive, and connects that call to theVoicemail system 142.

In normal manner, the caller leaves a message for the called user, andthis message is stored in a dynamically allocated memory area of theVoicemail system 142, and is associated with an identifier for thatcalled user for retrieval purposes.

When the NSS 116 connects that call to the Viocemail system 142, it alsoalerts the data store manager 152, which responds by sending a retrievalrequest to the Voicemail system 142 in respect of that called user. Whenthe Voicemail system 142 completes the recording process for thatmessage, it notifies the data store manager 152, and sends a copy ofthat message. If this the first message to be stored in the data store150 for that user, the data store manager 152 allocates a respectivememory area 154 and writes that message to that memory area. The datastore manager 152 associates with that message, in known manner, asequence identifier to aid retrieval. Subsequent messages are written tothat respective memory area 154, and data store manager 152 can createda data object comprising all the messages in that respective memory are154. For the purpose of this description, such a data object is referredto as a Mobile Home (MH). Each MH is unique to its associated user.

The PLR 148 records the current location of the MHs of certain users.The GSM networks 100 might be organised such that every user has arespective MH. Alternatively, an HM might only be created upon userrequest. e.g. only users who roam outside their home network wouldrequire an MH, and for this case the GSM network 100 will be of a hybridarrangement, including both a home location register and a PLR.

In one variant, the subsequent messages are written to individual memoryareas 154, and the data store manager 152 keeps a record of all messagesassociated with that user. In this case, the data store manager 152 cancreate a single data object comprising all the messages in thoseindividual memory areas 154. In another variant, the data store 150 andthe data store manager 152 are replaced by a data object manager (notshown) which is arranged, upon command, to retrieve a user's messagesfrom the Voicemail system 142 and create a data object comprising allthose retrieved messsages.

In a first example scenario, suppose that there are number ofinterconnected GEM networks 100-1, 100-2, 100-3 etc., providing “global”mobile communications coverage, it being understood that “global” is notbeing used in its literal sense, but that such coverage is widespreadover the world. Each GEM network has an identifier of the major city ofits country (and time zone of that country, if applicable), e.g. London(100-1), Tokyo (100-2), New York (100-3), etc., and for convenience theGEM networks are synonymously referred to herein by their identifier,e.g. if an MH is resident in the London GEM network 100-1, this isalternatively stated as the MH being resident in London, or just being“in London”, and, correspondingly, the associated user is said to behosted in London. Similarly, a user who is currently registered with theLondon GEM network 100-1 is said to be “registered with London” or “inLondon”.

Suppose that a user A, who had previously been hosted in London and hashis user identity “A” recorded in its PLR 148 as currently having his MHresident in London, travels to Japan and switches on his mobiletelephone to register with Tokyo. Having registered with Tokyo, user Adecides that he wants to retrieve his Voicemail messages, and makes arequest to Tokyo for his MH to be moved to his current location.

Tokyo has a respective PLR 148 including an entry for user A, recordingthe current location of his MH as London. Tokyo accesses its PLR 148,ascertains that user A's MH is in London, and sends a query message toLondon to check that the MH is indeed in London, and then, upon receiptof a positive response from London, sends a move message commandingLondon to send the MH to Tokyo. In a variant, London responds to receiptof the query message by sending the MH, and the move message is omitted.The PLRs 148 are situated at the point of ingress to their respectivenetworks so as to minimise transmission delays when responding to userrequests for MHs to be moved to a remote network.

Upon receipt of that move message, London, using its data manager 152will create user A's MH from the stored Voicemail messages and part ofuser A's profile data relating to PLR update information and sent thatMH to Tokyo. The PLR update information defines which networks are to beinformed when an MH moves from one network to another, and in thisexample suppose that user A has selected his PLR update information tobe “London”, “Tokyo” and “New York”. Thus, the PLRs in only these threenetworks record the current location of user A's MH. User A will selectthe specified networks of his PLR update information on the basis ofwhere he expects the majority of his incoming calls to originate.However, if he does not wish to select specified networks, he can select“all” networks, but this is not as efficient.

Tokyo will retrieve the PLR update information from user A's MH and sendan update message to London and New York, so that they can update therespective entries for user A in their PLR 148 by replacing “London”with “Tokyo”, and will also update its own PLR 148.

User A can now access the Voicemail service, and Tokyo will provideinstructions in the language corresponding to a language identifier heldin the profile data in the MH. User A can retrieve his messages directlyfrom the MH, which is currently resident in Tokyo. If the MH hadremained resident in London, then the retrieval of his messages mightwell be affected by, e.g. transmission congestion.

If a user B, currently registered with New York, now makes a call touser A, New York refers to its PLR 148, ascertains that user A's MH iscurrently in Tokyo, and attempts to set up a connection with user A. Ifuser A is available, the call is connected to user A over a singletransmission link from New York to Tokyo. If user A is not available,user B can effectively leave a Voicemail message in user A's MH, forlocal retrieval by user A when he next accesses his Voicemail messages.Thus, any user currently registered with any of user A's update networkswill be able to connect to user A over a minimum length transmissionlink, e.g. for a calling user C in Tokyo, the call will be a local callstaying within Tokyo.

A further advantage is that if a user D in Tokyo makes a call to user A,Tokyo will access its PLR 148 to see whether there is an entry for userA, and find that user A is currently in Tokyo, so a connection can bemade by means of a local call.

Suppose now a first variation where user A's PLR update information is“London” and “New York”, i.e. Tokyo's PLR has not been kept up to date,so that when user A requests that his MH be moved to Tokyo, his currentMH location (London) cannot be found in Tokyo's PLR 148. The samecondition results for a variant Tokyo network which is not equipped witha PLR.

There are a number of options. In a first option, Tokyo ascertains byanalysis of user A's telephone number the identity of his home network,and sends a query message to that home network to check that the MH isin that network. If the home network replies that it does not store thatMH, then Tokyo broadcasts such a query message to call GEM networksother that the home network. Any network storing an MH for which itreceives a query message will respond by sending a reply messageindicating that the MH is in that network. In a second option, forfinding the location of the MH in as short a time as possible, thesequery function are combined and Tokyo sends a single broadcast querymessage to all GMS networks.

In this variation, when Tokyo receives user A's MH from London, only NewYork and London will update their PLRs 148. Now, when user D makes acall to user A, Tokyo's PLR has no current location information for userA, and a standard call set up procedure is initiated in which Tokyomakes a call to user A's home network and that call is “tromboned” backto Tokyo. Not only is such a call expensive because it involves two longinternational routes, but also the set up time is noticeably longbecause of the call processing that the home network has to do. Thus,the advantage of avoiding tromboned calls is obtained when the remotenetwork has its PLR 148 updated.

The MH can include part of the user-associated profile relating to callhandling, e.g. Do Not Disturb data for blocking onward connectionaccording to time of day, using either the time zone in which the PLR isresident or time zone in which the MH is resident, or data for blockingonward connection on the basis of a distance threshold, using eithergeographic or hopcount metric. And in this case, this call handling datacan be sent to each of the specified networks of a user's PLR updateinformation and stored in the respective PLRs 148. thus, in the aboveexample, when user B in New York makes a call to user A in Tokyo, theNew York PLR is accessed to find the current location of user A, anduser A's call handling data is retrieved and analysed to see whether NewYork can proceed to handle the call. If the result of the analysis isthat the call is not to be connected through to Tokyo, the call handlingdata may provide that the call be connected to New York's Voicemailsystem. The presence of user A's call handling data in the New York PLRis referred to as remote presence.

User A can select different call handling data for different ones of thespecified networks of his PLR update information. Such differentiatedremote presence may be based on network location or some other strategicfactor.

Whereas the above description is based on the concept of users of GEMnetworks moving from one network to another, the present invention isalso applicable to software agents which travel between interconnecteddata networks on a global scale, and such software agents constitutemobile objects of the present invention. A travelling software agentmight want other software agents to be able to communicate with it, sothe software agent has an associated MH, the data networks have PLRs,and when such a software agent travels to a remote network it sends forits MH to be forwarded from its previous hosting network and updates thePLRs of all or a selected set of data networks. Thus, the term “user” asused herein includes such software agents.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise”, “comprising” and thelike are to be construed in an inclusive as opposed to an exclusive orexhaustive sense; that is to say, in the sense of “including, but notlimited to”,

What is claimed is:
 1. A method of operating a communications networkinterconnected with a plurality of other communications networks, themethod comprising the steps of: establishing data storage and a locationregister having entries comprising a user identifier and an associatedlocation identifier; and responding to an originating call to a calleduser by accessing the location register in accordance with a useridentifier for that called user to ascertain the correspondingassociated location identifier, and if there is a corresponding entry,and performing connection set up on the basis that the destinationnetwork for the called user is that communications network whichcorresponds to that ascertained location identifier; the method beingcharacterised in that: a user-associated relocatable data packagescurrently located at said communications network are stored in said datastorage, and each said location identifier represents the most recentlocation known to said communications network of the correspondinguser-associated relocatable data package; and the method beingcharacterised by the steps of: receiving from a said othercommunications network a move request in respect of a specified user,and in response, removing that specified user's associated relocatabledata package from the data storage, and relocating that data package tosaid other communications network.
 2. A method as claimed in claim 1,including the step of responding to receipt from said othercommunications network of a location register update message in respectof that specified user by changing the location identifier of thatspecified user's entry to that for said other communications network. 3.A method as claimed in claim 1, including the steps of: receiving arequest from a user, currently registered with said communicationsnetwork as a visitor, for that visiting user's associated relocatabledata package to be relocated to said communications network; in responseto that receipt, accessing the location register in accordance with anidentifier for that visiting user; and, if there is a correspondingentry, ascertaining the location identifier of that corresponding entry,and sending a move request in respect of that visiting user to the othercommunications network corresponding to the ascertained locationidentifier, else, requesting of at least one of the other communicationsnetworks a location identifier for the other communications networkcurrently storing that visiting user's associated relocatable datapackage. upon receipt of the requested location identifier, sending amove request in respect of that visiting user to the othercommunications network corresponding to the received locationidentifier; and upon receipt of that user's associated relocatable datapackage, storing it in the data storage.
 4. A method as claimed in claim3, including the steps of retrieving instructions from a receiveduser-associated relocatable data package. arid in accordance with thoseinstructions, effecting modification of each of a predetermined set ofthe communications networks.
 5. A method as claimed in claim 4, whereinthe step of effecting modification comprises generating a message andsending that message to each of said predetermined set of thecommunications networks other than that communications network whichperforms the step of retrieving instructions.
 6. A method as claimed inclaim 4, wherein those instructions comprise instructions for modifyingthe respective location registers by changing the respective storedlocation identifier to that of the network which performs the step ofretrieving instructions.
 7. A method as claimed in claim 4, whereinthose instructions comprise instructions for storing call handlinginformation and modifying the respective location registers to associatethat stored call handling information with the entry corresponding tothe received user-associated relocatable data package.
 8. A method asclaimed in claim 3, wherein the requesting step comprises sending aquery message in respect of that visiting user to that one of said othercommunications networks which corresponds to the global address of thatvisiting user.
 9. A method as claimed in claim 3, wherein the requestingstep comprises sending a query message in respect of that visiting userto each of said other communications networks.
 10. A method of operatinga communications network interconnected with a plurality of othercommunications networks, at least one of said other communicationsnetworks operating in accordance with claim 1, the method comprising thesteps of: receiving a request from a user, currently registered withsaid communications network as a visitor, for that visiting user'sassociated relocatable data package to be relocated to saidcommunications network; in response to that receipt, requesting of atleast one of the other communications networks a location identifier forthe other communications network currently storing that visiting user'sassociated relocatable data package; upon receipt of the requestedlocation identifier, sending to the other communications networkcorresponding to the received location identifier a move request forthat user's associated relocatable data package to be relocated to saidcommunications network, and upon receipt of that user's associatedrelocatable data package, storing it in association with a useridentifier for that user.
 11. A method as claimed in claim 1, includingthe steps of connecting calls for a particular user, whoseuser-associated relocatable data package is currently located at saidcommunications network, to a message recording service and recordingmessages, and incorporating those recorded messages within thatparticular user's relocatable data package.
 12. A communications networkarranged for interworking with a plurality of other communicationsnetworks and employing a global addressing scheme, the networkcomprising: a location register arranged to store entries eachcomprising a user identifier and an associated location identifier; andmeans arranged to respond to an originating call to a called user byaccessing the location register in accordance with an identifier forthat called user and ascertaining the associated location identifier,and performing connection set up on the basis that the destinationnetwork for the called user is that communications network whichcorresponds to that ascertained location identifier; wherein the networkis characterised by: data storing means arranged to storeuser-associated relocatable data packages; means arranged to respond toreceipt from a said other communications network of a move request inrespect of a specified user's associated relocatable data package storedin the data storing means by removing that specified user's associatedrelocatable data package from the data storing means, and relocatingthat data package to said other communications network.
 13. A network asclaimed in claim 12, including means arranged to respond to receipt fromsaid other communications network of a message in respect of thatspecified user and containing location register update information bychanging the location identifier of that specified user's entry to thatfor said other communications network.
 14. A network as claimed in claim12, including means arranged to respond to a request from a visitinguser for that visiting user's associated relocatable data package to bemoved to said communications network, by accessing the location registerin accordance with an identifier for that visiting user, and, if thereis a corresponding entry, ascertaining the associated locationidentifier, and sending a move request in respect of that visiting userto a said other communications network corresponding to the ascertainedlocation identifier, else requesting of at least one of the othercommunications networks a location identifier for the othercommunications network currently storing that visiting users associatedrelocatable data package, and, upon receipt of the requested locationidentifier, sending a move request in respect of that visiting user tothat other communications network corresponding to that receivedlocation identifier.
 15. A network as claimed claim 14, including meansarranged to retrieve instructions from a received user's relocatabledata package, and in accordance with those instructions, to effectmodification of each of a predetermined set of the communicationsnetworks.
 16. A network as claimed in claim 15, wherein the retrievingand modifying means is arranged to effect said modification bygenerating a message and sending that message to each of saidpredetermined set of the communications networks other than itself. 17.A network as claimed in claim 15, wherein the retrieving and modifyingmeans is arranged, in accordance with those instructions, to modify therespective location register by changing the respective stored locationidentifier to its own location identifier.
 18. A network as claimed inclaim 15, for use when those instructions comprise instructions forstoring call handling information, and wherein the retrieving andmodifying means is arranged to modify the respective location registerto associate such stored call handling information with the entrycorresponding to the received user-associated relocatable data package.19. A network as claimed in claim 14, and arranged to make said requestof at least one of the other communications networks for said networkidentifier by sending a query message in respect of that visiting userto that one of said other communications networks which corresponds tothe global address of that visiting user.
 20. A network as claimed inclaim 14, and arranged to make said request of at least one of the othercommunications networks for said network identifier by sending a querymessage in respect of that visiting user to each of said othercommunications networks.
 21. A communications network arranged forinterworking with a plurality of other communications networks, at leastone of said other communications networks being in accordance with claim12, said communications network comprising: a location register arrangedto store entries each comprising a user identifier and an associatedlocation identifier; and means arranged to respond to an originatingcall to a called user by accessing the location register in accordancewith an identifier for that called user and ascertaining the associatedlocation identifier, and performing connection set up on the basis thatthe destination network for the called user is that communicationsnetwork which corresponds to that ascertained location identifier;wherein the network is characterised by: data storing means; and meansarranged to respond to a request from a user, currently registered withsaid communications network as a visitor, for that user's associatedrelocatable data package to be moved to said communications network byrequesting of at least one of the other communications networks alocation identifier for the other communications network currentlystoring that visiting user's associated data package, upon receipt ofthe requested network identifier, sending to the other communicationsnetwork corresponding to the received location identifier a move requestfor that user's associated data package to be relocated to saidcommunications network, and upon receipt of that user's associatedrelocatable data package, storing it in said data storing means inassociation with a user identifier for that user.
 22. A network asclaimed in claim 12, having a message recording system, and includingmeans arranged to respond to messages recorded by the message recordingsystem in respect of a particular user whose relocatable data package iscurrently stored in said data storing means by incorporating thoserecorded messages within that particular user's relocatable datapackage.